1. Field of the Invention:
This invention relates generally to fastener driving tools and more particularly pertains to a tool adapted to removably receive on the drive end of its rotatable shaft a drive socket for engaging and manipulating pairs of fasteners, such as nuts and bolts, wherein the tool's shaft has an axial bore opening on the face of its drive end permitting a non-rotatable auxiliary tool shank to extend through the shaft outward from the shaft's drive end. The auxiliary tool shank serves the purpose of engaging and preventing rotation of a first fastener of a pair of fasteners to be joined or separated while the second fastener of the pair is rotatably driven relative to the first.
2. Description of the Prior Art:
In the prior art there are various types of wrenches manually operated or motor driven, utilizing a rotatable shaft which is driven to impart rotative motion to a socket engaged on a bolt head or a nut. Such sockets are available in various standard sizes for selected utilization with different size fasteners, and generally have square rear hole or opening to enable fitting the socket onto the drive end of the rotatable shaft of the wrench being utilized. The drive end of the shaft is square in cross section and of a size to be inserted into the square hole of the socket, forming a driving engagement therewith.
A socket driving tool may alternatively be provided with a drive end other than the familiar type which is square in cross section, such as a five-sided or hexagonal drive end or a spline configuration. Sockets for these alternative drive end configurations are, of course, adapted inwardly with an accommodating mating configuration to enable manual installation and removal of the socket onto the drive end. It is contemplated that the invention described herein may be utilized on various drive end configurations, although the preferred embodiment herein described and illustrated is of the square-end type.
Various means have been heretofore provided, on the drive end of such a wrench shaft, to cause a tight gripping action between the drive end and the internal surface of the rear end portion of the socket so that the socket will not, slide from its mounted position on the drive end until it is purposely manually disengaged therefrom by pulling it away. The common characteristic of such engagement means for holding a socket on a shaft drive end is the use of a biasing or spring means carried on the drive end which is adapted to have a part thereof depressed inwardly as a function of the socket being slid to its operative position on the drive end whereby outward holding pressure is exerted against the inside surface of the socket, usually in cooperation with an internal annular groove or detent provided on the inside socket surface.
One form of such engaging means is achieved by providing an annular groove near the end of the shaft drive end in which resides a circular inwardly depressible wire spring. The act of inserting the socket onto the drive end causes the wire spring to depress momentarily inwardly until the socket is in its fully installed position on the drive end whereupon the circular spring extends outwardly to engage an annular groove inside the socket to prevent the socket from slipping away from its installed position. Purposeful manual removal of the socket will cause the circular spring to depress inwardly into the groove onto the shaft drive end as the rear portion of the socket passes thereover. This type of engaging means is taught in U.S. Pat. No. 1,469,589 where a spring metal ring, carried in an annular groove, is provided on a bar-like manual socket wrench which is hexagonal in cross section. Similarly, U.S. Pat. Nos. 2,704,681 and 3,752,514 disclose the provision of circular spring means at the outer end of a drive shaft of an impact wrench where the drive end is square in cross section. This type of socket engagement arrangement is advantageous on an impact wrench or any other type of wrench wherein the drive shaft is subject to extreme shock during use, since the drive end is solid and has no openings crossing through its axis which would tend to weaken it and thereby shorten its life.
Another form of engagement means which is commonly utilized at the present time in hand-manipulated socket wrenches is the provision, on a square drive end of a drive shaft, of a depressible hemispheric button or ball detent which projects slightly above one side surface of the drive end. An internal cross bore in the drive end beneath the button houses a spring which urges the button to its normal projecting position, and the button is depressed inwardly as a function of the socket being slid into its operative position on the shaft drive. When the socket reaches its operative position, the button pops outwardly into a groove inside the socket to thereby grip the socket.
At least one prior art patent teaches the use in combination of the encircling ring concept and the depressible button concept. In U.S. Pat. No. 3,752,514, this arrangement may be found wherein a button is normally pushed to its outward projecting position by rearwardly-extending legs of an encircling front-mounted spring ring.
While socket engagement arrangements as heretofore described are unquestionably useful in certain applications, they also have inherent disadvantages in certain specific applications. Where it is desired to have an axial bore through the rotatable drive shaft of a wrench, to accommodate an auxiliary tool extending therethrough, as provided in such U.S. Pat. Nos. as 3,323,394, 3,323,395 and 3,696,693, the use of an annular groove and/or a cross bore in the shaft drive end to accommodate a spring means may be impossible or highly impractical. More specifically, where an axial center bore is provided in a shaft drive end of predetermined outside dimensions, the provision therewith of an annular groove about the drive end can significantly weaken the drive end in the area of the annular groove or cause sufficient reduction of the diameter of the axial bore that it cannot accommodate the extension of an auxiliary tool, such as a screw driver shank therethrough, as taught, for example, in the aforementioned U.S. Pat. No. 3,323,394. Obviously, a laterally directed cross-bore housing a spring for a depressible button would be unacceptable in such a tool because it would intersect the axial bore.